The footprint of a transistor for a specific circuit is at least partially a function of the output current required by the circuit. A semiconductor device having a relatively low on-resistance can have a relative high output current and, consequently, can have a smaller footprint.
An ideal transistor has zero resistance in the on state and infinite resistance in the off state. However, the on-resistance of a transistor is determined by numerous factors and is generally not zero. Channel resistance and drift region resistance are two most significant factors that contribute to on-resistance. Accordingly, reductions in the channel resistance or the drift region resistance of a semiconductor device can lead to a decrease in the device's on-resistance, which may help to limit the footprint of the device.